Airport navigation light unit and system

ABSTRACT

An airport navigation light unit wherein connection elements for supply lines, a lighting device, a sensor device, a switching device and a communication device are provided in a base body The switching device and the communication device are connected to the connection elements. The communication device switches the switching device, according to control signals which are transmitted via the supply lines, which switches the lighting device on to the connection elements. The sensor device detects a state prevailing outside the airport navigation light unit and transmits it to the communication device which determines a useful signal therefrom which it feeds to the supply lines. The control signals and the useful signal are transmitted as OFDM signals via the supply lines. An airport navigation light system comprises a plurality of said airport navigation units.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to the European application No.03006362.2, filed Mar. 20, 2003 and to the International Application No.PCT/EP2004/002926, filed Mar. 19, 2004 which are incorporated byreference herein in their entirety.

FIELD OF INVENTION

The present invention relates to an airport navigation light unitcomprising a base body in which connection elements for connectingsupply lines, a lighting device, a sensor device, a switching device anda communication device are arranged. The present invention relatesfurthermore to an airport navigation light system comprising a powersupply device, a central communication unit assigned to said powersupply device and a plurality of airport navigation light units, theairport navigation light units being connected via supply lines to thepower supply device.

BACKGROUND OF INVENTION

Airport navigation light units of this type and airport navigation lightsystems of this type are generally known.

Thus, from DE 101 04 950 A1, for example, an airport navigation lightunit of this type is known in which the switching device and thecommunication device are connected to the connection elements. Theswitching device can be switched by the communication device accordingto control signals which are transmitted to the communication device viathe supply lines. As a result, the lighting device can be switched on tothe connection elements by means of the switching device. An internaloperating state of the lighting device can be detected by means of thesensor device and transmitted to the communication device. The rawsignal can then be fed to the supply lines. Also known from thispublication is an associated airport navigation light system in whichthe central communication unit is also connected to the supply lines.

Such an airport navigation light unit is also known from DE 199 49 737A1. In the case of this airport navigation light unit, only theswitching device is connected to the connection elements. According tocontrol signals transmitted via a separate communication path, theswitching unit can be switched by the communication device, so thelighting device can be switched on to the connection elements by meansof the switching device. A state prevailing outside the airportnavigation light unit can be detected by means of the sensor device andtransmitted as a raw signal to the communication device. The raw signalcan be evaluated by the communication device and a useful signaldetermined therefrom transmitted via the separate communication path. Acorresponding airport navigation light system is also known from thispublication.

An airport navigation light unit of this type is also disclosed in theearlier German patent application 102 33 437.4, not subject to priorpublication at the time of filing. In the case of this airportnavigation light unit, both the switching device and the communicationdevice are connected to the connection elements. The switching devicecan be switched by the communication device according to control signalswhich are transmitted to the communication device via the supply line,so the lighting device can be switched on to the connection elements bymeans of the switching device. A state prevailing inside the airportnavigation light unit can be detected by means of the sensor device andtransmitted to the communication device. The state can relate inparticular to the operating state of the lighting device. The raw signalcan be fed by the communication device to the supply lines. The controlsignals and the useful signal are transmitted as OFDM signals via thesupply lines.

In the aforementioned patent application, not subject to priorpublication, there is also disclosed an airport navigation light systemcomprising a power supply device, a central communication unit assignedto the power supply device and a plurality of airport navigation lightunits. The airport navigation light units are connected via the samesupply lines both to the power supply device and to the centralcommunication unit.

From U.S. Pat. No. 5,426,429 an airport navigation light unit is knowncomprising a base body which has connection elements for connectingsupply lines and in which a lighting device, a switching device and acommunication device are arranged. The switching device and thecommunication device are connected to the connection elements. Theswitching device can be switched by the communication device accordingto control signals transmitted via the supply lines to the communicationdevice, so the lighting device can be switched on to the connectionelements by means of the switching device. A sensor device can beconnected to the airport navigation light unit, by means of which sensordevice a state prevailing outs ide the airport navigation light unit canbe detected and transmitted as a raw signal to the communication device.The raw signal can be evaluated by the communication device and a usefulsignal determined therefrom can be fed to the supply lines.

SUMMARY OF INVENTION

An object of the present invention is to create an airport navigationlight unit and an airport navigation light system correspondingherewith, in which complex states prevailing outside the airportnavigation light unit can also be detected simply and yet safely andreliably and can be transmitted to a central communication unitsuperordinate to the airport navigation light unit. In the event thatthe airport navigation light unit is connected via a transformer to aseries power supply circuit, data transmission should essentially beindependent of the length of a spur line from the transformer to theairport navigation light unit.

The object is achieved by the claims.

If the OFDM signals can be transmitted in a frequency range between 20and 160 kHz, the airport navigation light unit operates particularlyreliably, for below a lower threshold frequency of 20 kHz disruptionsoccur through thyristor-controlled current regulators. Above an upperthreshold frequency of 160 kHz, the low-pass behavior of thetransmission medium (cable, transformer) hampers communication. The OFDMsignals can be transmitted in a plurality of non-overlapping frequencybands. Each frequency band has a bandwidth. If the communication deviceis fashioned such that the bandwidth of the frequency bands can beparameterized, the bandwidth used can be adapted to the data throughputrequired and to the data security required.

If the communication device is fashioned such that a signal transmissionrequest can be fed by it to the supply lines, active reporting of asignal transmission is possible (in contrast to a purely passiveresponse to a request by the central communication unit).

Alternatively or additionally, it is also possible for the communicationdevice to be fashioned such that the useful signal can be fed by it tothe supply lines unrequested.

If the communication device has an intelligent programmable unit, e.g. amicroprocessor or a microcontroller, the communication device and withit the airport navigation light unit can be flexibly adapted and/orupdated.

If the communication device determines from the raw signal as a usefulsignal at least the presence or absence of an object, in particular ametal object, e.g. an aircraft, the airport navigation light unit isdesigned for a particularly frequent application case. More detailedinformation about the object, e.g. a classification or type-coding ofthe object, a speed measurement or a distance measurement, canoptionally also be provided.

If the sensor device has at least one magnetic-field sensor and/or atleast one radar sensor, it can be manufactured particularly reliably andcost-effectively.

Alternatively or additionally, the communication device can alsodetermine using the raw signal as a useful signal an—in particularmeteorological—environmental characteristic, e.g. the temperature, thewind speed or precipitation.

If a transformer is connected upstream of the connection elements, theairport navigation light unit can advantageously be connected to aseries power supply circuit. Due to the use of OFDM signals for datatransmissions, a spur line from the transformer to the airportnavigation light unit can have a line length exceeding 5 meters. Inparticular, the spur line can be up to 200 meters long.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages and details will emerge from the descriptionhereinbelow of an exemplary embodiment in conjunction with the drawings,in which

FIG. 1 shows a schematic diagram of an airport navigation light unit and

FIGS. 2-4 each show a schematic diagram of an airport navigation lightunit.

DETAILED DESCRIPTION OF INVENTION

According to FIG. 1, an airport navigation light system has a powersupply device 1 and a plurality of airport navigation light units 2. Theairport navigation light units 2 are connected to the power supplydevice 1 via supply lines 3. The supply lines 3 form a series powersupply circuit to which the airport navigation light units 2 areconnected. The supply lines 3 could, however, also form a parallel powercircuit.

A central communication unit 4 is assigned to the power supply device 1.The central communication unit 4 is looped in to the supply lines 3. Theairport navigation light units 2 are therefore connected via the samesupply lines 3 to both the power supply device 1 and the centralcommunication unit 4.

The central communication unit 4 is connected, e.g. via a localconnecting network 5, to a master computer 6. The central communicationunit 4 receives from the master computer 6 firstly setpoint inputs whichit forwards to the airport navigation light units 2. Secondly, itreceives from the airport navigation light units 2 status reports whichit forwards to the master computer 6. The master computer 6 is in thisway able to effect an airport management system, as described, forexample, in DE 101 04 950 A1, DE 199 49 737 A1 or EP 0 883 873 B1.

According to FIG. 2, each airport navigation light unit 2 has a basebody 7. Connection elements 8 are arranged in the base body 7 forconnecting the supply lines 3, a lighting device 9, a sensor device 10,a switching device 11 and a communication device 12. The lighting device9 has at least one, optionally also a plurality of lights. The sensordevice has at least one sensor. The switching device 11 has one switchper light outlet from the light.

The switching device 11 and the communication device 12 are connected tothe connection elements 8. A transformer 13 is connected upstream of theconnection elements 8. The transformer 13 enables the connection, asshown in FIG. 1, of the airport navigation light units 2 to the seriespower supply circuit. The connection is effected via spur lines 3′ whichhave a line length 1. The line length 1 can be greater than 5 meters, inparticular also greater than 10 meters. In a particular case, it can beup to 200 meters but, where possible, 100 to 150 meters should not beexceeded.

Control signals S can be transmitted by the central communication unit 4via the supply lines 3 to the communication device 12. The transmissionof control signals S is effected, as can be seen from FIGS. 1 and 2, asan OFDM signal, to be precise preferably in a frequency range between 20and 160 kHz. A lower threshold frequency of 30, or better 45 or 55 kHz,should not be undershot and an upper threshold frequency of 145 or 155kHz should not be exceeded.

The switching device 11 is switched by the communication device 12according to the control signals S transmitted. In this way, thelighting device 9 can be connected to or separated from the connectionelements 8 by means of the switching device 11. Here, the switchingdevice 11 is preferably fashioned as an electronic switching device 11.In principle, however, it would also be possible for it to be fashionedas an electromechanical switch 11.

The sensor device 10 has at least one sensor 14 and at least one sensor15. By means of the sensor 14, an internal state of the airportnavigation light unit 2 can be detected and transmitted to thecommunication device 12. For example, by means of the sensor 14 it canbe detected whether current is flowing through the lighting device 9 ornot. In conjunction with the desired switching state of the lightingdevice 9, which desired state is known to the communication device 12due to the transmitted control signal S, this communication device 12can consequently determine whether the lighting device 9 is defective. Acorresponding feedback message M (e.g. switched on—switchedoff—flashing—defective) can optionally be transmitted by thecommunication device 12 via the supply lines 3 to the centralcommunication unit 4. The feedback message M also is optionallytransmitted as an OFDM signal via the supply lines 3. The frequencyrange in this case is preferably the same as that used in thetransmission of control signals S.

By means of the sensor 15, a state which prevails out side the airportnavigation light unit 2 can be detected. This signal can be transmittedas a raw signal R to the communication device 12. The raw signal R canbe evaluated by this communication device 12 and a useful signal Ndetermined therefrom. The useful signal N can be fed in the same manneras the feedback message M, i.e. as an OFDM signal in the frequency rangebetween 30 (35, 45) and 160 (155, 145) kHz, to the supply lines 3 andcan in this way be transmitted to the central communication unit 4.

The communication device 12 contains according to FIG. 2 an intelligentprogrammable unit 16, e.g. a microprocessor or a microcontroller. Aprogram memory 17 and a working memory 18 are assigned to theintelligent unit 16. The program memory 17 is a read-only memory. It ispreferably electrically erasable and re-writable. Reprogramming of thecommunication device 12 is possible by this means—possibly even via thesupply lines 3. The working memory 18 can be a—possiblybuffered—volatile memory (RAM).

The transmission of OFDM signals is effected in a plurality of frequencybands which each have a bandwidth, but do not overlap. In particular,the bandwidth of the frequency bands is determined here by the programfiled in the program memory 17. The communication device 12 is thusfashioned such that the bandwidth of the frequency bands can beparameterized.

According to FIG. 2, the airport navigation light unit 2 has two sensors15 which are fashioned according to FIG. 2 as magnetic-field sensors(MFS). The presence or absence of an object 19 can be detected in asimple manner by means of the magnetic-field sensors 15 shown in FIG.2—particularly if the airport navigation light unit 2 is installed in atake-off runway, a landing runway or a taxiway of an airport. Thisapplies quite particularly when the object 19 is a metal object, e.g. anaircraft 19 or a motor vehicle. However, the detection of alien objects19 on landing runways and taxiways is also possible.

The communication device 12 is therefore preferably programmed such thatit determines from the raw signal R a useful signal N that indicatesthis presence or absence. Given correspondingly precise evaluation ofthe raw signal R, a finer differentiation of the useful signal N canoptionally also be made. For example, a type classification(A310—B737—DC10—motor vehicle—other object) can be carried out. Due tothe presence of two sensors 15, the speed of the object 19 when crossingthe airport navigation light unit 2 can also be determined.

If the airport navigation light units 2 operate on the basis ofsynchronization on a shared time base, it is also possible to transmit,together with the detection of an object 19, the respective detectiontime to the central communication unit 4. In this case, determination ofthe speed of the object 19 is also possible when the airport navigationlight units 2 have only a single magnetic-field sensor.

The magnetic-field sensors 15 detect the geomagnetic field and itsdistortion along at least one axis. The detection axis in this case isvertical. In the case of dual-axis detection, the geomagnetic field ispreferably additionally detected transversely to the direction oftaxiing. Regarding the reasons for this, the reader is referred to EP 1193 662 A1 (see FIG. 5 there).

FIG. 3 shows a similar airport navigation light unit 2 to that shown inFIG. 2. By contrast with FIG. 2, however, the sensor device 10 has anexternal sensor 15′ which is fashioned as a radar sensor. In otherrespects, the mode of operation of the airport navigation light unit 2shown in FIG. 3 is identical to that shown in FIG. 2.

As an alternative to or in addition to detecting an object 19 accordingto FIGS. 2 and 3, the airport navigation light unit 2—see also FIG.4—can also contain a further external sensor 15″. Its raw signal R isevaluated by the communication device 12 in such a way that thiscommunication device determines a useful signal N therefrom in respectof a meteorological environmental characteristic. The meteorologicalenvironmental characteristic can, for example, be the temperature, thewind speed, precipitation (e.g. rain, snow) or visibility conditions(e.g. day/night/fog).

Other characteristics can also—alternatively or additionally—be detectedby means of the sensor device 10. Examples of such characteristics arevibrations, noises, air or ground humidity and internal states of theairport navigation light unit 2. In particular also, special sensors canbe used for this. Furthermore, the detection of objects can also beeffected with sensors other than radar or magnetic-field sensors. Forexample, optical sensors (especially cameras) can be used.

In all cases, i.e. both in the embodiment according to FIG. 2 and in theembodiment according to FIG. 3 or the embodiment according to FIG. 4,the evaluation and categorization of the raw signal is thus effected bythe communication device 12. The evaluation result is then transmittedby the communication device 12 via the supply lines 3 to the centralcommunication unit 4.

In the case of prior-art airport navigation light systems it has to datebeen usual for the airport navigation light units 2 to be purely passivecomponents. The communication devices 12 are thus specifically addressedby the central communication unit 4 and then respond to this addressing.

In contrast to this, the communication devices 12 according to FIGS. 2to 4 are fashioned such that they can also feed a signal transmissionrequest e.g. in the form of an interrupt request IR, to the supply lines3. If, for example, one of the communication devices 12 notices a defectin the lighting device 9, it feeds the signal transmission request IR tothe supply lines 3. The signal transmission request IR is received andevaluated by the central communication unit 4. It can therefore in thenext step address in a targeted manner the communication device 12 whichhas sent the signal transmission request IR. The sending communicationdevice 12 can optionally also transmit, in addition to its address, acode, from which the central communication unit can recognize the typeof signals to be transmitted. For example, different codes can be usedfor recognizing an object 19, for modifying a meteorological identifyingcharacteristic or for modifying an internal state of an airportnavigation light unit (e.g. failure of the lighting device 9).

It is even possible for the communication devices 12 to feed not only aninterrupt request IR but immediately the useful signal N itself to thesupply lines. In this case, however, collision monitoring, which isgenerally known from computer networks, must be carried out.

The transformers 13 are optimized for operating in the series powersupply circuit. They are essentially designed for optimizing powertransmission, but not for optimizing signal transmission. They thereforedampen the transmitted signals S, M, N, IR relatively severely. For thisreason, the communication devices 12 preferably have repeaters forsignal conditioning and amplification and means for measuring thereception strength and quality of the transmitted signals S, M, N, IR.The reception strength and quality is also preferably transmitted viathe supply lines 3 to the central communication unit 4. The centralcommunication unit 4 thus constantly receives a picture of the overallcommunication system. By evaluating the information transmitted abouttransmission quality and signal strength, the central communication unit4 is consequently able to configure the overall communication systemdynamically—optionally even optimally for each individual transmissionoperation. In particular, the central communication unit 4 can, bytransmitting corresponding control signals S, stipulate which of thecommunication devices 12 is to perform repeater functions in each caseand which not. In this way, adequate transmission quality in thecommunication system is constantly ensured. At the same time, the poweroutlay needed for this, as well as crosstalk behavior and backgroundnoise, can be optimized through dynamic adaptation of the communicationnetwork.

1.-12. (canceled)
 13. An Airport navigation light unit, comprising: abase body; connection elements arranged in the base body for connectingsupply lines; a lighting device; a sensor device; a switching device;and a communication device, the switching device and the communicationdevice connected to the connection elements, wherein the switchingdevice is configured to be switched by the communication device based oncontrol signals transmitted to the communication device via the supplylines for switching the lighting device to the connection elements usingthe switching device, the sensor device is configured to detect a stateprevailing outside the airport navigation light unit and to transmit thedetected stated in form of a raw signal to the communication device, thecommunication device is configured to evaluate the raw signal, togenerate a wanted signal based on the evaluated raw signal, and to feedthe wanted signal to the supply line, and the control signals and thewanted signal are transmitted via the supply lines in the form of OFDMsignals.
 14. The Airport navigation light unit according to claim 13,wherein the OFDM signals are transmitted in a frequency range between 20and 160 kHz.
 15. The Airport navigation light unit according to claim13, wherein the OFDM signals are transmitted in a plurality ofnon-overlapping frequency bands, and the communication device isconfigured to parametrize the bandwidth of the frequency bands.
 16. TheAirport navigation light unit according to claim 13, wherein thecommunication device is further configured to feed a signal transmissionrequest to the supply lines.
 17. The Airport navigation light unitaccording to claim 13, wherein the communication device is furtherconfigured to unsolicitedly feed the wanted signal to the supply lines.18. The Airport navigation light unit according to claim 13, wherein thecommunication device includes an intelligent programmable unit.
 19. TheAirport navigation light unit according to claim 18, wherein theintelligent programmable unit is a microprocessor or a microcontroller.20. The Airport navigation light unit according to claim 13, wherein thewanted signal-includes information on the presence or absence of anobject.
 21. The Airport navigation light unit according to claim 20,wherein the object is a metal object.
 22. The Airport navigation lightunit according to claim 21, wherein the metal object is an aircraft. 23.The Airport navigation light unit according to claim 13, wherein thesensor device includes a magnetic-field sensor or a radar sensor. 24.The Airport navigation light unit according to claim 13, wherein thewanted signal includes an environmental characteristic.
 25. The Airportnavigation light unit according to claim 24, wherein the environmentalcharacteristic is a meteorological characteristic.
 26. The Airportnavigation light unit according to claim 25, wherein the meteorologicalcharacteristic is an ambient temperature, a wind speed or a currentprecipitation.
 27. The Airport navigation light unit according to claim13, further comprising a transformer connected upstream of theconnection elements.
 28. An Airport navigation light system, comprising:a power supply device; a central communication unit assigned to thepower supply device; and a plurality of airport navigation light units,each navigation light unit comprising: a base body; connection elementsarranged in the base body for connecting supply lines; a lightingdevice; a sensor device; a switching device; and a communication device,the switching device and the communication device connected to theconnection elements, wherein the switching device is configured to beswitched by the communication device based on control signalstransmitted to the communication device via the supply lines forswitching the lighting device to the connection elements using theswitching device, the sensor device is configured to detect a stateprevailing outside the airport navigation light unit and to transmit thedetected stated in form of a raw signal to the communication device, thecommunication device is configured to evaluate the raw signal, togenerate a wanted signal based on the evaluated raw signal, and to feedthe wanted signal to the supply line, and the control signals and thewanted signal are transmitted via the supply lin es in the form of OFDMsignals, wherein the airport navigation light units are connected bothto the power supply device and to the central communication unit usingthe same supply lines.
 29. The Airport navigation light system accordingto claim 28, wherein the supply lines form a series power supplycircuit, the airport navigation light units are connected to the seriespower supply circuit via transformers and spur lines, and at least oneof the spur lines has a line length between 5 and 200 meters.